VI improver, dispersant, and antioxidant additive and lubricating oil composition

A composition according to claim in which said copolymer has an average molecular weight from about 25,000 to 250,000.

A lubricating oil composition comprising a major amount of an oil of lubricating viscosity and a minor amount effective to impart viscosity index, dispersancy, and antioxidant properties to said oil of an additive composition prepared by the steps comprising:

• (a) reacting a styrene-ethylenebutylene-styrene block copolymer having styrene-ethylenebutylene-styrene molecular weight ratios, respectively, of 1:6:1 to 1:3:1 characterized in that unsaturation in the styrene blocks in equal to or greater than 50 percent and the ethylenebutylene block is hydrogenated leaving no more than 10 percent unsaturation, with at least one olefinic carboxylic acid acylating agent to form one or more acylating reaction intermediates characterized by having a carboxylic acid acylating function within their structure, and
• (b) reacting said reaction intermediate in (a) with a hydrocarbon substituted or unsubstituted N-naphthyl-phenylenediamine represented by the formula:
• ##STR5## in which each of R', R" and R'" represent hydrogen or an alkyl radical having from 1 to 5 carbon atoms.